breakpoint()

void breakpoint(void)

The breakpoint() action induces a kernel breakpoint, causing the system to stop
and transfer control to the kernel debugger. The kernel debugger will emit
a string denoting the DTrace probe that triggered the action. For example,
if one were to do the following:

The address following the probe description is the address of the enabling
control block (ECB) within DTrace. You can use this address
to determine more details about the probe enabling that induced the breakpoint
action.

A mistake with the breakpoint() action may cause
it to be called far more often than intended. This behavior might in turn
prevent you from even terminating the DTrace consumer that is triggering the
breakpoint actions. In this situation, set the kernel integer variable dtrace_destructive_disallow to 1. This setting will disallow all destructive
actions on the machine. Apply this setting only in this
particular situation.

The exact method for setting dtrace_destructive_disallow will
depend on the kernel debugger that you are using. If using the OpenBoot PROM
on a SPARC system, use w!:

ok 1 dtrace_destructive_disallow w!
ok

Confirm that the variable has been set using w?:

ok dtrace_destructive_disallow w?
1
ok

Continue by typing go:

ok go

If using kmdb(1) on
x86 or SPARC systems, use the 4–byte write modifier (W)
with the / formatting dcmd: